Trigger group for semi-automatic firearms

1. A trigger assembly for a firearm comprising:

a frame;

a hammer connected to the frame and movable between a cocked position and a striking position;

the hammer being biased toward the striking position;

a trigger element connected to the frame and movable by a user between a forward position and a rearward position;

a selector connected to the frame and movable between at least a first position and a second position;

a plurality of retention facilities each operable to selectively restrain the hammer in the cocked position, and when the selector is in the first position to enable discharge of the firearm in response to movement of the trigger to the rearward position, and when the selector is in the second position to enable discharge of the firearm in response to movement of the trigger to the forward position after movement to the rearward position.

2. The trigger assembly of claim 1 including a first retention facility and second retention facility operable when the selector is in the first position to release the hammer when the trigger is pulled to the rearward position to discharge the firearm and to retain the hammer in the rearward position while the trigger remains in the rearward position after discharge of the firearm and after the trigger is returned to the forward position.

3. The trigger assembly of claim 2 including a third retention facility and fourth retention facility operable when the selector is in the second position to restrain the hammer in the cocked position when the trigger is moved to the rearward position, to release the hammer to discharge the firearm when the trigger is moved to the forward position after the trigger is pulled to the rearward position, and to restrain the hammer in the cocked position after discharge of the firearm.

4. The trigger assembly of claim 3 wherein the frame includes a cam surface, and at least one of the first, second, third, and fourth retention facilities has a cam follower adapted to follow the cam surface and generate a movement of the at least one of the first, second, third, and fourth retention facilities to cease restraint of the hammer by the at least one of the first, second, third, and fourth retention facilities.

5. The trigger assembly of claim 3 wherein when the selector is in the second position, the third retention facility is operable to restrain the hammer in the cocked position, and to release the hammer to restraint by the fourth retention facility in response to moving the trigger to the rearward position.

6. The trigger assembly of claim 3 wherein at least one of the first and second retention facilities and at least one of the third and fourth retention facilities comprise a set of adjacent retention facilities operable to engage adjacent portions of a common portion of the hammer.

7. The trigger assembly of claim 6 wherein adjacent retention facilities are each planar elements parallel to and adjacent to each other.

8. The trigger assembly of claim 1 wherein the selector includes a block element operable to prevent movement of the selector from the first position to the second position while the hammer is being restrained by any of the retention facilities.

9. The trigger assembly of claim 8 wherein the block element is interoperable in response to depression of the hammer by a bolt carrier to separate the hammer from all retention facilities, the hammer operable to move at least one of the retention facilities away from the block element to enable movement of the selector from the first position to the second position.

10. A trigger group for a firearm comprising:

a frame;

a hammer connected to the frame and movable between a cocked position and a striking position;

the hammer being biased toward the striking position;

a trigger element connected to the frame and movable by a user between a forward position and a rearward position;

a selector connected to the frame and movable between at least a first position and a second position;

a movable first hammer retention facility responsive to movement of the trigger element;

when selector is in the first position, the trigger element is in the forward position, and the hammer is in the cocked position, the first hammer retention facility being operable to engage the hammer to restrain the hammer in the cocked position, and in response to pulling the trigger element to the rearward position to release the hammer to the striking position to discharge the firearm;

a disconnector assembly connected to the frame and operably connected to the selector and having a second hammer retention facility operable when the selector is in the first position to restrain the hammer in the cocked position after discharge of the firearm while the trigger is maintained in the rearward position;

the disconnector assembly having a third hammer retention facility operable when the selector is in the second position to restrain the hammer in the cocked position; and

the disconnector assembly having a fourth hammer retention facility operable when the selector is in the second position to restrain the hammer in the cocked position in response to movement of the trigger to the rearward position, and in response to movement of the trigger element to the forward position to release the hammer to the striking position to discharge the firearm.

11. The trigger group of claim 10 wherein the frame includes a cam surface, and at least one of the first, second, third, and fourth retention facilities has a cam follower adapted to follow the cam surface and generate a movement of the at least one of the first, second, third, and fourth retention facilities to cease restraint of the hammer by the at least one of the first, second, third, and fourth retention facilities.

12. The trigger group of claim 10 wherein the frame includes a cam surface, and the third retention facility has a cam follower adapted to follow the cam surface and generate a movement of the third retention facility to cease restraint of the hammer by the third retention facility.

13. The trigger group of claim 10 wherein when the selector is in the second position, the third retention facility is operable to restrain the hammer in the cocked position, and to release the hammer to restraint by the fourth retention facility in response to moving the trigger to the rearward position.

14. The trigger group of claim 10 wherein the second retention facility and the fourth retention facility comprise a set of adjacent retention facilities operable to engage adjacent portions of a common portion of the hammer.

15. The trigger group of claim 14 wherein the adjacent retention facilities are each planar elements parallel to and adjacent to each other.

16. The trigger group of claim 10 wherein the selector includes a block element operable to prevent movement of the selector from the first position to the second position while the hammer is being restrained by any of the retention facilities.

17. The trigger group of claim 16 wherein the block element is interoperable in response to depression of the hammer by a bolt carrier to separate the hammer from all retention facilities, the hammer operable to move at least one of the retention facilities away from the block element to enable movement of the selector from the first position to the second position.

18. The trigger group of claim 10 wherein the selector has a third position in which discharge of the firearm is prevented.